Theory of the Electronic and Optical Properties of Dilute Bismide Quantum Well Lasers

We present a theoretical study of the gain characteristics of GaBi_xAs_1-x/(Al)GaAs dilute bismide quantum well (QW) lasers. After providing a brief overview of the current state of development of dilute bismide alloys for semiconductor laser applications, we introduce the theoretical model we have developed for the description of the electronic and optical properties of dilute bismide QWs. Using a theoretical approach based on a 12-band k·p Hamiltonian we then undertake a detailed analysis of the electronic and optical properties of a series of ideal and real GaBixAs_1-x/(Al)GaAs QW laser structures as a function of Bi composition x. We theoretically optimize the gain characteristics of an existing low x device by varying the Al composition in the barrier layers, which governs a trade-off between the electronic and optical confinement. The theoretical results are compared to temperature-dependent spontaneous emission measurements at low x, which reveals the presence of significant Bi-induced inhomogeneous broadening of the optical spectra. We also investigate the gain characteristics of GaBixAs_1-x/(Al)GaAs QW lasers at higher values of x, including a QW designed to emit at 1.55 μm. Our theoretical results elucidate the impact of Bi incorporation on the electronic and optical properties of GaAs-based QW lasers, and reveal several general trends in the gain characteristics as a function of x. Overall, our analysis confirms that dilute bismide alloys are a promising candidate material system for the development of highly efficient, uncooled GaAs-based QW lasers operating at telecommunication wavelengths.